This proposal describes a five year plan for Alexander Soukas to transition to an independently-funded investigator with expertise in functional genomics of obesity and diabetes. Dr. Soukas, an instructor in medicine and assistant in molecular biology at Massachusetts General Hospital, will be mentored by Gary Ruvkun, Ph.D., professor of genetics at Harvard Medical School. Dr. Ruvkun is a worldwide expert in C. elegans biology, metabolism, genetics, and genomics, a Lasker Award winner, and has a very strong record of mentorship, having supervised 38 trainees, 24 of which have academic, tenure-track faculty positions. An advisory committee of physician-scientists with expertise in human genetics, lipid metabolism, cell signaling, and mitochondrial biology made up of David Altshuler, M.D., Ph.D., Joseph Avruch, M.D., Mason Freeman, M.D., and Vamsi Mootha, M.D. will provide scientific direction, ground the investigator in medically-relevant lines of research, and provide career guidance during the transition to independent investigator. Dr. Soukas will carry out the planned career development activities in the research and training environment at the Massachusetts General Hospital and Harvard Medical School. The research program proposes use of the organism C. elegans to identify candidate genes involved in the pathogenesis of obesity and diabetes. Obesity and type 2 diabetes are extremely prevalent, highly associated diseases that cost the US more than $174 billion in 2007, and produce an even greater cost on society in terms of life-years lost. Given the tremendous conservation in ancient pathways regulating energy homeostasis, we hypothesize that identification of conserved genes regulating fat in C. elegans will illuminate human genetic pathways regulating energy homeostasis, and possibly even obesity and diabetes disease mechanisms. Preliminary studies on C. elegans have isolated more than 50 mutants with altered fat content. Those most notable identified to date are the conserved genes rictor, an essential component of target of rapamycin complex 2 (TORC2) protein kinase, and serum and glucocorticoid-induced kinase (sgk-1), an Akt-related kinase that acts downstream of TORC2. Completed studies of C. elegans rictor indicate that it is a central regulator of metabolism, controlling fat mass, growth, reproduction, and lifespan through regulation of the kinases AKT and SGK4. The investigator will learn to apply genomics (RNA interference, whole-genome sequencing, high-throughput technology), forward genetics, and biochemistry 1) to identify new mutations in genes that alter C. elegans fat content, 2) to determine the cellular and molecular mechanism by which altered fat mass is generated in rictor/TORC2 and other mutants, and 3) build a network of genetic interactions regulating body fat. The ultimate goals of this work are to identify and characterize genes that play a conserved role in energy homeostasis in C. elegans and humans, to inform human genetic and mouse model studies of obesity and diabetes, and to transition to independent investigator status.